diff options
Diffstat (limited to 'doc/android')
| -rw-r--r-- | doc/android/ab.rst (renamed from doc/android/ab.txt) | 39 | ||||
| -rw-r--r-- | doc/android/avb2.rst | 133 | ||||
| -rw-r--r-- | doc/android/avb2.txt | 115 | ||||
| -rw-r--r-- | doc/android/bcb.rst | 100 | ||||
| -rw-r--r-- | doc/android/bcb.txt | 89 | ||||
| -rw-r--r-- | doc/android/boot-image.rst | 154 | ||||
| -rw-r--r-- | doc/android/fastboot-protocol.rst (renamed from doc/android/fastboot-protocol.txt) | 45 | ||||
| -rw-r--r-- | doc/android/fastboot.rst (renamed from doc/android/fastboot.txt) | 92 | ||||
| -rw-r--r-- | doc/android/index.rst | 14 |
9 files changed, 489 insertions, 292 deletions
diff --git a/doc/android/ab.txt b/doc/android/ab.rst index 9f37ed5c58..961895c32e 100644 --- a/doc/android/ab.txt +++ b/doc/android/ab.rst @@ -1,3 +1,5 @@ +.. SPDX-License-Identifier: GPL-2.0+ + Android A/B updates =================== @@ -7,41 +9,44 @@ Overview A/B system updates ensures modern approach for system update. This feature allows one to use two sets (or more) of partitions referred to as slots (normally slot A and slot B). The system runs from the current slot while the -partitions in the unused slot can be updated [1]. +partitions in the unused slot can be updated [1]_. A/B enablement -------------- The A/B updates support can be activated by specifying next options in -your board configuration file: +your board configuration file:: CONFIG_ANDROID_AB=y CONFIG_CMD_AB_SELECT=y The disk space on target device must be partitioned in a way so that each partition which needs to be updated has two or more instances. The name of -each instance must be formed by adding suffixes: _a, _b, _c, etc. -For example: boot_a, boot_b, system_a, system_b, vendor_a, vendor_b. +each instance must be formed by adding suffixes: ``_a``, ``_b``, ``_c``, etc. +For example: ``boot_a``, ``boot_b``, ``system_a``, ``system_b``, ``vendor_a``, +``vendor_b``. -As a result you can use 'ab_select' command to ensure A/B boot process in your +As a result you can use ``ab_select`` command to ensure A/B boot process in your boot script. This command analyzes and processes A/B metadata stored on a -special partition (e.g. "misc") and determines which slot should be used for +special partition (e.g. ``misc``) and determines which slot should be used for booting up. Command usage ------------- +.. code-block:: none + ab_select <slot_var_name> <interface> <dev[:part_number|#part_name]> -for example: +for example:: => ab_select slot_name mmc 1:4 -or +or:: => ab_select slot_name mmc 1#misc -Result: +Result:: => printenv slot_name slot_name=a @@ -49,19 +54,19 @@ Result: Based on this slot information, the current boot partition should be defined, and next kernel command line parameters should be generated: - - androidboot.slot_suffix= - - root= +* ``androidboot.slot_suffix=`` +* ``root=`` -For example: +For example:: androidboot.slot_suffix=_a root=/dev/mmcblk1p12 -A/B metadata is organized according to AOSP reference [2]. On the first system -start with A/B enabled, when 'misc' partition doesn't contain required data, -the default A/B metadata will be created and written to 'misc' partition. +A/B metadata is organized according to AOSP reference [2]_. On the first system +start with A/B enabled, when ``misc`` partition doesn't contain required data, +the default A/B metadata will be created and written to ``misc`` partition. References ---------- -[1] https://source.android.com/devices/tech/ota/ab -[2] bootable/recovery/bootloader_message/include/bootloader_message/bootloader_message.h +.. [1] https://source.android.com/devices/tech/ota/ab +.. [2] https://android.googlesource.com/platform/bootable/recovery/+/refs/tags/android-10.0.0_r25/bootloader_message/include/bootloader_message/bootloader_message.h diff --git a/doc/android/avb2.rst b/doc/android/avb2.rst new file mode 100644 index 0000000000..a072119574 --- /dev/null +++ b/doc/android/avb2.rst @@ -0,0 +1,133 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Android Verified Boot 2.0 +========================= + +This file contains information about the current support of Android Verified +Boot 2.0 in U-Boot. + +Overview +-------- + +Verified Boot establishes a chain of trust from the bootloader to system images: + +* Provides integrity checking for: + + * Android Boot image: Linux kernel + ramdisk. RAW hashing of the whole + partition is done and the hash is compared with the one stored in + the VBMeta image + * ``system``/``vendor`` partitions: verifying root hash of dm-verity hashtrees + +* Provides capabilities for rollback protection + +Integrity of the bootloader (U-Boot BLOB and environment) is out of scope. + +For additional details check [1]_. + +AVB using OP-TEE (optional) +^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +If AVB is configured to use OP-TEE (see `Enable on your board`_) rollback +indexes and device lock state are stored in RPMB. The RPMB partition is managed +by OP-TEE (see [2]_ for details) which is a secure OS leveraging ARM +TrustZone. + +AVB 2.0 U-Boot shell commands +----------------------------- + +Provides CLI interface to invoke AVB 2.0 verification + misc. commands for +different testing purposes:: + + avb init <dev> - initialize avb 2.0 for <dev> + avb verify - run verification process using hash data from vbmeta structure + avb read_rb <num> - read rollback index at location <num> + avb write_rb <num> <rb> - write rollback index <rb> to <num> + avb is_unlocked - returns unlock status of the device + avb get_uuid <partname> - read and print uuid of partition <partname> + avb read_part <partname> <offset> <num> <addr> - read <num> bytes from + partition <partname> to buffer <addr> + avb write_part <partname> <offset> <num> <addr> - write <num> bytes to + <partname> by <offset> using data from <addr> + +Partitions tampering (example) +------------------------------ + +Boot or system/vendor (dm-verity metadata section) is tampered:: + + => avb init 1 + => avb verify + avb_slot_verify.c:175: ERROR: boot: Hash of data does not match digest in + descriptor. + Slot verification result: ERROR_IO + +Vbmeta partition is tampered:: + + => avb init 1 + => avb verify + avb_vbmeta_image.c:206: ERROR: Hash does not match! + avb_slot_verify.c:388: ERROR: vbmeta: Error verifying vbmeta image: + HASH_MISMATCH + Slot verification result: ERROR_IO + +Enable on your board +-------------------- + +The following options must be enabled:: + + CONFIG_LIBAVB=y + CONFIG_AVB_VERIFY=y + CONFIG_CMD_AVB=y + +In addtion optionally if storing rollback indexes in RPMB with help of +OP-TEE:: + + CONFIG_TEE=y + CONFIG_OPTEE=y + CONFIG_OPTEE_TA_AVB=y + CONFIG_SUPPORT_EMMC_RPMB=y + +Then add ``avb verify`` invocation to your android boot sequence of commands, +e.g.:: + + => avb_verify=avb init $mmcdev; avb verify; + => if run avb_verify; then \ + echo AVB verification OK. Continue boot; \ + set bootargs $bootargs $avb_bootargs; \ + else \ + echo AVB verification failed; \ + exit; \ + fi; \ + + => emmc_android_boot= \ + echo Trying to boot Android from eMMC ...; \ + ... \ + run avb_verify; \ + mmc read ${fdtaddr} ${fdt_start} ${fdt_size}; \ + mmc read ${loadaddr} ${boot_start} ${boot_size}; \ + bootm $loadaddr $loadaddr $fdtaddr; \ + +If partitions you want to verify are slotted (have A/B suffixes), then current +slot suffix should be passed to ``avb verify`` sub-command, e.g.:: + + => avb verify _a + +To switch on automatic generation of vbmeta partition in AOSP build, add these +lines to device configuration mk file:: + + BOARD_AVB_ENABLE := true + BOARD_AVB_ALGORITHM := SHA512_RSA4096 + BOARD_BOOTIMAGE_PARTITION_SIZE := <boot partition size> + +After flashing U-Boot don't forget to update environment and write new +partition table:: + + => env default -f -a + => setenv partitions $partitions_android + => env save + => gpt write mmc 1 $partitions_android + +References +---------- + +.. [1] https://android.googlesource.com/platform/external/avb/+/master/README.md +.. [2] https://www.op-tee.org/ diff --git a/doc/android/avb2.txt b/doc/android/avb2.txt deleted file mode 100644 index 48e9297c75..0000000000 --- a/doc/android/avb2.txt +++ /dev/null @@ -1,115 +0,0 @@ -Android Verified Boot 2.0 - -This file contains information about the current support of Android Verified -Boot 2.0 in U-boot - -1. OVERVIEW ---------------------------------- -Verified Boot establishes a chain of trust from the bootloader to system images -* Provides integrity checking for: - - Android Boot image: Linux kernel + ramdisk. RAW hashing of the whole - partition is done and the hash is compared with the one stored in - the VBMeta image - - system/vendor partitions: verifying root hash of dm-verity hashtrees. -* Provides capabilities for rollback protection. - -Integrity of the bootloader (U-boot BLOB and environment) is out of scope. - -For additional details check: -https://android.googlesource.com/platform/external/avb/+/master/README.md - -1.1. AVB using OP-TEE (optional) ---------------------------------- -If AVB is configured to use OP-TEE (see 4. below) rollback indexes and -device lock state are stored in RPMB. The RPMB partition is managed by -OP-TEE (https://www.op-tee.org/) which is a secure OS leveraging ARM -TrustZone. - - -2. AVB 2.0 U-BOOT SHELL COMMANDS ------------------------------------ -Provides CLI interface to invoke AVB 2.0 verification + misc. commands for -different testing purposes: - -avb init <dev> - initialize avb 2.0 for <dev> -avb verify - run verification process using hash data from vbmeta structure -avb read_rb <num> - read rollback index at location <num> -avb write_rb <num> <rb> - write rollback index <rb> to <num> -avb is_unlocked - returns unlock status of the device -avb get_uuid <partname> - read and print uuid of partition <partname> -avb read_part <partname> <offset> <num> <addr> - read <num> bytes from -partition <partname> to buffer <addr> -avb write_part <partname> <offset> <num> <addr> - write <num> bytes to -<partname> by <offset> using data from <addr> - - -3. PARTITIONS TAMPERING (EXAMPLE) ------------------------------------ -Boot or system/vendor (dm-verity metadata section) is tampered: -=> avb init 1 -=> avb verify -avb_slot_verify.c:175: ERROR: boot: Hash of data does not match digest in -descriptor. -Slot verification result: ERROR_IO - -Vbmeta partition is tampered: -=> avb init 1 -=> avb verify -avb_vbmeta_image.c:206: ERROR: Hash does not match! -avb_slot_verify.c:388: ERROR: vbmeta: Error verifying vbmeta image: -HASH_MISMATCH -Slot verification result: ERROR_IO - - -4. ENABLE ON YOUR BOARD ------------------------------------ -The following options must be enabled: -CONFIG_LIBAVB=y -CONFIG_AVB_VERIFY=y -CONFIG_CMD_AVB=y - -In addtion optionally if storing rollback indexes in RPMB with help of -OP-TEE: -CONFIG_TEE=y -CONFIG_OPTEE=y -CONFIG_OPTEE_TA_AVB=y -CONFIG_SUPPORT_EMMC_RPMB=y - -Then add `avb verify` invocation to your android boot sequence of commands, -e.g.: - -=> avb_verify=avb init $mmcdev; avb verify; -=> if run avb_verify; then \ - echo AVB verification OK. Continue boot; \ - set bootargs $bootargs $avb_bootargs; \ - else \ - echo AVB verification failed; \ - exit; \ - fi; \ - -=> emmc_android_boot= \ - echo Trying to boot Android from eMMC ...; \ - ... \ - run avb_verify; \ - mmc read ${fdtaddr} ${fdt_start} ${fdt_size}; \ - mmc read ${loadaddr} ${boot_start} ${boot_size}; \ - bootm $loadaddr $loadaddr $fdtaddr; \ - -If partitions you want to verify are slotted (have A/B suffixes), then current -slot suffix should be passed to 'avb verify' sub-command, e.g.: - -=> avb verify _a - -To switch on automatic generation of vbmeta partition in AOSP build, add these -lines to device configuration mk file: - -BOARD_AVB_ENABLE := true -BOARD_AVB_ALGORITHM := SHA512_RSA4096 -BOARD_BOOTIMAGE_PARTITION_SIZE := <boot partition size> - -After flashing U-boot don't forget to update environment and write new -partition table: -=> env default -f -a -=> setenv partitions $partitions_android -=> env save -=> gpt write mmc 1 $partitions_android diff --git a/doc/android/bcb.rst b/doc/android/bcb.rst new file mode 100644 index 0000000000..8861608300 --- /dev/null +++ b/doc/android/bcb.rst @@ -0,0 +1,100 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Android Bootloader Control Block (BCB) +====================================== + +The purpose behind this file is to: + +* give an overview of BCB w/o duplicating public documentation +* describe the main BCB use-cases which concern U-Boot +* reflect current support status in U-Boot +* mention any relevant U-Boot build-time tunables +* precisely exemplify one or more use-cases + +Additions and fixes are welcome! + +Overview +-------- + +Bootloader Control Block (BCB) is a well established term/acronym in +the Android namespace which refers to a location in a dedicated raw +(i.e. FS-unaware) flash (e.g. eMMC) partition, usually called ``misc``, +which is used as media for exchanging messages between Android userspace +(particularly recovery [1]_) and an Android-capable bootloader. + +On higher level, BCB provides a way to implement a subset of Android +Bootloader Requirements [2]_, amongst which are: + +* Android-specific bootloader flow [3]_ +* Get the "reboot reason" (and act accordingly) [4]_ +* Get/pass a list of commands from/to recovery [1]_ +* TODO + + +'bcb'. Shell command overview +----------------------------- + +The ``bcb`` command provides a CLI to facilitate the development of the +requirements enumerated above. Below is the command's help message:: + + => bcb + bcb - Load/set/clear/test/dump/store Android BCB fields + + Usage: + bcb load <dev> <part> - load BCB from mmc <dev>:<part> + bcb set <field> <val> - set BCB <field> to <val> + bcb clear [<field>] - clear BCB <field> or all fields + bcb test <field> <op> <val> - test BCB <field> against <val> + bcb dump <field> - dump BCB <field> + bcb store - store BCB back to mmc + + Legend: + <dev> - MMC device index containing the BCB partition + <part> - MMC partition index or name containing the BCB + <field> - one of {command,status,recovery,stage,reserved} + <op> - the binary operator used in 'bcb test': + '=' returns true if <val> matches the string stored in <field> + '~' returns true if <val> matches a subset of <field>'s string + <val> - string/text provided as input to bcb {set,test} + NOTE: any ':' character in <val> will be replaced by line feed + during 'bcb set' and used as separator by upper layers + + +'bcb'. Example of getting reboot reason +--------------------------------------- + +.. code-block:: bash + + if bcb load 1 misc; then + # valid BCB found + if bcb test command = bootonce-bootloader; then + bcb clear command; bcb store; + # do the equivalent of AOSP ${fastbootcmd} + # i.e. call fastboot + else if bcb test command = boot-recovery; then + bcb clear command; bcb store; + # do the equivalent of AOSP ${recoverycmd} + # i.e. do anything required for booting into recovery + else + # boot Android OS normally + fi + else + # corrupted/non-existent BCB + # report error or boot non-Android OS (platform-specific) + fi + + +Enable on your board +-------------------- + +The following Kconfig options must be enabled:: + + CONFIG_PARTITIONS=y + CONFIG_MMC=y + CONFIG_BCB=y + +.. [1] https://android.googlesource.com/platform/bootable/recovery +.. [2] https://source.android.com/devices/bootloader +.. [3] https://patchwork.ozlabs.org/patch/746835/ + ("[U-Boot,5/6] Initial support for the Android Bootloader flow") +.. [4] https://source.android.com/devices/bootloader/boot-reason diff --git a/doc/android/bcb.txt b/doc/android/bcb.txt deleted file mode 100644 index 7b7177cacf..0000000000 --- a/doc/android/bcb.txt +++ /dev/null @@ -1,89 +0,0 @@ -Android Bootloader Control Block (BCB) - -The purpose behind this file is to: - - give an overview of BCB w/o duplicating public documentation - - describe the main BCB use-cases which concern U-Boot - - reflect current support status in U-Boot - - mention any relevant U-Boot build-time tunables - - precisely exemplify one or more use-cases - -Additions and fixes are welcome! - - -1. OVERVIEW ---------------------------------- -Bootloader Control Block (BCB) is a well established term/acronym in -the Android namespace which refers to a location in a dedicated raw -(i.e. FS-unaware) flash (e.g. eMMC) partition, usually called "misc", -which is used as media for exchanging messages between Android userspace -(particularly recovery [1]) and an Android-capable bootloader. - -On higher level, BCB provides a way to implement a subset of Android -Bootloader Requirements [2], amongst which are: - - Android-specific bootloader flow [3] - - Get the "reboot reason" (and act accordingly) [4] - - Get/pass a list of commands from/to recovery [1] - - TODO - - -2. 'BCB'. SHELL COMMAND OVERVIEW ------------------------------------ -The 'bcb' command provides a CLI to facilitate the development of the -requirements enumerated above. Below is the command's help message: - -=> bcb -bcb - Load/set/clear/test/dump/store Android BCB fields - -Usage: -bcb load <dev> <part> - load BCB from mmc <dev>:<part> -bcb set <field> <val> - set BCB <field> to <val> -bcb clear [<field>] - clear BCB <field> or all fields -bcb test <field> <op> <val> - test BCB <field> against <val> -bcb dump <field> - dump BCB <field> -bcb store - store BCB back to mmc - -Legend: -<dev> - MMC device index containing the BCB partition -<part> - MMC partition index or name containing the BCB -<field> - one of {command,status,recovery,stage,reserved} -<op> - the binary operator used in 'bcb test': - '=' returns true if <val> matches the string stored in <field> - '~' returns true if <val> matches a subset of <field>'s string -<val> - string/text provided as input to bcb {set,test} - NOTE: any ':' character in <val> will be replaced by line feed - during 'bcb set' and used as separator by upper layers - - -3. 'BCB'. EXAMPLE OF GETTING REBOOT REASON ------------------------------------ -if bcb load 1 misc; then - # valid BCB found - if bcb test command = bootonce-bootloader; then - bcb clear command; bcb store; - # do the equivalent of AOSP ${fastbootcmd} - # i.e. call fastboot - else if bcb test command = boot-recovery; then - bcb clear command; bcb store; - # do the equivalent of AOSP ${recoverycmd} - # i.e. do anything required for booting into recovery - else - # boot Android OS normally - fi -else - # corrupted/non-existent BCB - # report error or boot non-Android OS (platform-specific) -fi - - -4. ENABLE ON YOUR BOARD ------------------------------------ -The following Kconfig options must be enabled: -CONFIG_PARTITIONS=y -CONFIG_MMC=y -CONFIG_BCB=y - -[1] https://android.googlesource.com/platform/bootable/recovery -[2] https://source.android.com/devices/bootloader -[3] https://patchwork.ozlabs.org/patch/746835/ - ("[U-Boot,5/6] Initial support for the Android Bootloader flow") -[4] https://source.android.com/devices/bootloader/boot-reason diff --git a/doc/android/boot-image.rst b/doc/android/boot-image.rst new file mode 100644 index 0000000000..195da688f4 --- /dev/null +++ b/doc/android/boot-image.rst @@ -0,0 +1,154 @@ +.. SPDX-License-Identifier: GPL-2.0+ +.. sectionauthor:: Sam Protsenko <joe.skb7@gmail.com> + +Android Boot Image +================== + +Overview +-------- + +Android Boot Image is used to boot Android OS. It usually contains kernel image +(like ``zImage`` file) and ramdisk. Sometimes it can contain additional +binaries. This image is built as a part of AOSP (called ``boot.img``), and being +flashed into ``boot`` partition on eMMC. Bootloader then reads that image from +``boot`` partition to RAM and boots the kernel from it. Kernel than starts +``init`` process from the ramdisk. It should be mentioned that recovery image +(``recovery.img``) also has Android Boot Image format. + +Android Boot Image format is described at [1]_. At the moment it can have one of +next image headers: + +* v0: it's called *legacy* boot image header; used in devices launched before + Android 9; contains kernel image, ramdisk and second stage bootloader + (usually unused) +* v1: used in devices launched with Android 9; adds ``recovery_dtbo`` field, + which should be used for non-A/B devices in ``recovery.img`` (see [2]_ for + details) +* v2: used in devices launched with Android 10; adds ``dtb`` field, which + references payload containing DTB blobs (either concatenated one after the + other, or in Android DTBO image format) + +v2, v1 and v0 formats are backward compatible. + +Android Boot Image format is represented by :c:type:`struct andr_img_hdr` in +U-Boot, and can be seen in ``include/android_image.h``. U-Boot supports booting +Android Boot Image and also has associated command + +Booting +------- + +U-Boot is able to boot the Android OS from Android Boot Image using ``bootm`` +command. In order to use Android Boot Image format support, next option should +be enabled:: + + CONFIG_ANDROID_BOOT_IMAGE=y + +Then one can use next ``bootm`` command call to run Android: + +.. code-block:: bash + + => bootm $loadaddr $loadaddr $fdtaddr + +where ``$loadaddr`` - address in RAM where boot image was loaded; ``$fdtaddr`` - +address in RAM where DTB blob was loaded. + +And parameters are, correspondingly: + + 1. Where kernel image is located in RAM + 2. Where ramdisk is located in RAM (can be ``"-"`` if not applicable) + 3. Where DTB blob is located in RAM + +``bootm`` command will figure out that image located in ``$loadaddr`` has +Android Boot Image format, will parse that and boot the kernel from it, +providing DTB blob to kernel (from 3rd parameter), passing info about ramdisk to +kernel via DTB. + +DTB and DTBO blobs +------------------ + +``bootm`` command can't just use DTB blob from Android Boot Image (``dtb`` +field), because: + +* there is no DTB area in Android Boot Image before v2 +* there may be several DTB blobs in DTB area (e.g. for different SoCs) +* some DTBO blobs may have to be merged in DTB blobs before booting + (e.g. for different boards) + +So user has to prepare DTB blob manually and provide it in a 3rd parameter +of ``bootm`` command. Next commands can be used to do so: + +1. ``abootimg``: manipulates Anroid Boot Image, allows one to extract + meta-information and payloads from it +2. ``adtimg``: manipulates Android DTB/DTBO image [3]_, allows one to extract + DTB/DTBO blobs from it + +In order to use those, please enable next config options:: + + CONFIG_CMD_ABOOTIMG=y + CONFIG_CMD_ADTIMG=y + +For example, let's assume we have next Android partitions on eMMC: + +* ``boot``: contains Android Boot Image v2 (including DTB blobs) +* ``dtbo``: contains DTBO blobs + +Then next command sequence can be used to boot Android: + +.. code-block:: bash + + => mmc dev 1 + + # Read boot image to RAM (into $loadaddr) + => part start mmc 1 boot boot_start + => part size mmc 1 boot boot_size + => mmc read $loadaddr $boot_start $boot_size + + # Read DTBO image to RAM (into $dtboaddr) + => part start mmc 1 dtbo dtbo_start + => part size mmc 1 dtbo dtbo_size + => mmc read $dtboaddr $dtbo_start $dtbo_size + + # Copy required DTB blob (into $fdtaddr) + => abootimg get dtb --index=0 dtb0_start dtb0_size + => cp.b $dtb0_start $fdtaddr $dtb0_size + + # Merge required DTBO blobs into DTB blob + => fdt addr $fdtaddr 0x100000 + => adtimg addr $dtboaddr + => adtimg get dt --index=0 $dtbo0_addr + => fdt apply $dtbo0_addr + + # Boot Android + => bootm $loadaddr $loadaddr $fdtaddr + +This sequence should be used for Android 10 boot. Of course, the whole Android +boot procedure includes much more actions, like: + +* obtaining reboot reason from BCB (see [4]_) +* implementing recovery boot +* implementing fastboot boot +* implementing A/B slotting (see [5]_) +* implementing AVB2.0 (see [6]_) + +But Android Boot Image booting is the most crucial part in Android boot scheme. + +All Android bootloader requirements documentation is available at [7]_. Some +overview on the whole Android 10 boot process can be found at [8]_. + +C API for working with Android Boot Image format +------------------------------------------------ + +.. kernel-doc:: common/image-android.c + :internal: + +References +---------- + +.. [1] https://source.android.com/devices/bootloader/boot-image-header +.. [2] https://source.android.com/devices/bootloader/recovery-image +.. [3] https://source.android.com/devices/architecture/dto/partitions +.. [4] :doc:`bcb` +.. [5] :doc:`ab` +.. [6] :doc:`avb2` +.. [7] https://source.android.com/devices/bootloader +.. [8] https://connect.linaro.org/resources/san19/san19-217/ diff --git a/doc/android/fastboot-protocol.txt b/doc/android/fastboot-protocol.rst index e9e7166a26..e723659e49 100644 --- a/doc/android/fastboot-protocol.txt +++ b/doc/android/fastboot-protocol.rst @@ -1,12 +1,13 @@ -FastBoot Version 0.4 ----------------------- +.. SPDX-License-Identifier: GPL-2.0+ + +FastBoot Version 0.4 +==================== The fastboot protocol is a mechanism for communicating with bootloaders over USB. It is designed to be very straightforward to implement, to allow it to be used across a wide range of devices and from hosts running Linux, Windows, or OSX. - Basic Requirements ------------------ @@ -66,31 +67,33 @@ Transport and Framing Example Session --------------- -Host: "getvar:version" request version variable +.. code-block:: none + + Host: "getvar:version" request version variable -Client: "OKAY0.4" return version "0.4" + Client: "OKAY0.4" return version "0.4" -Host: "getvar:nonexistant" request some undefined variable + Host: "getvar:nonexistant" request some undefined variable -Client: "OKAY" return value "" + Client: "OKAY" return value "" -Host: "download:00001234" request to send 0x1234 bytes of data + Host: "download:00001234" request to send 0x1234 bytes of data -Client: "DATA00001234" ready to accept data + Client: "DATA00001234" ready to accept data -Host: < 0x1234 bytes > send data + Host: < 0x1234 bytes > send data -Client: "OKAY" success + Client: "OKAY" success -Host: "flash:bootloader" request to flash the data to the bootloader + Host: "flash:bootloader" request to flash the data to the bootloader -Client: "INFOerasing flash" indicate status / progress - "INFOwriting flash" - "OKAY" indicate success + Client: "INFOerasing flash" indicate status / progress + "INFOwriting flash" + "OKAY" indicate success -Host: "powerdown" send a command + Host: "powerdown" send a command -Client: "FAILunknown command" indicate failure + Client: "FAILunknown command" indicate failure Command Reference @@ -105,6 +108,8 @@ Command Reference specification. OEM-specific commands should not begin with a lowercase letter, to prevent incompatibilities with future specs. +.. code-block:: none + "getvar:%s" Read a config/version variable from the bootloader. The variable contents will be returned after the OKAY response. @@ -139,16 +144,14 @@ Command Reference "powerdown" Power off the device. - - Client Variables ---------------- -The "getvar:%s" command is used to read client variables which +The ``getvar:%s`` command is used to read client variables which represent various information about the device and the software on it. -The various currently defined names are: +The various currently defined names are:: version Version of FastBoot protocol supported. It should be "0.3" for this document. diff --git a/doc/android/fastboot.txt b/doc/android/fastboot.rst index 9de13223f8..de3f6c37d7 100644 --- a/doc/android/fastboot.txt +++ b/doc/android/fastboot.rst @@ -1,12 +1,12 @@ -================ +.. SPDX-License-Identifier: GPL-2.0+ + Android Fastboot ================ Overview -======== +-------- -The protocol that is used over USB and UDP is described in -``doc/android/fastboot-protocol.txt``. +The protocol that is used over USB and UDP is described in [1]_. The current implementation supports the following standard commands: @@ -22,25 +22,23 @@ The current implementation supports the following standard commands: The following OEM commands are supported (if enabled): -- oem format - this executes ``gpt write mmc %x $partitions`` +- ``oem format`` - this executes ``gpt write mmc %x $partitions`` Support for both eMMC and NAND devices is included. Client installation -=================== +------------------- The counterpart to this is the fastboot client which can be found in Android's ``platform/system/core`` repository in the fastboot folder. It runs on Windows, Linux and OSX. The fastboot client is -part of the Android SDK Platform-Tools and can be downloaded from: - -https://developer.android.com/studio/releases/platform-tools +part of the Android SDK Platform-Tools and can be downloaded from [2]_. Board specific -============== +-------------- USB configuration ------------------ +^^^^^^^^^^^^^^^^^ The fastboot gadget relies on the USB download gadget, so the following options must be configured: @@ -57,7 +55,7 @@ supported by the fastboot client. The list of vendor IDs supported can be found in the fastboot client source code. General configuration ---------------------- +^^^^^^^^^^^^^^^^^^^^^ The fastboot protocol requires a large memory buffer for downloads. This buffer should be as large as possible for a @@ -67,46 +65,46 @@ may be overridden on the fastboot command line using ``-l`` and ``-s``. Fastboot environment variables -============================== +------------------------------ Partition aliases ------------------ +^^^^^^^^^^^^^^^^^ Fastboot partition aliases can also be defined for devices where GPT -limitations prevent user-friendly partition names such as "boot", "system" -and "cache". Or, where the actual partition name doesn't match a standard +limitations prevent user-friendly partition names such as ``boot``, ``system`` +and ``cache``. Or, where the actual partition name doesn't match a standard partition name used commonly with fastboot. The current implementation checks aliases when accessing partitions by name (flash_write and erase functions). To define a partition alias -add an environment variable similar to: +add an environment variable similar to:: -``fastboot_partition_alias_<alias partition name>=<actual partition name>`` + fastboot_partition_alias_<alias partition name>=<actual partition name> -for example: +for example:: -``fastboot_partition_alias_boot=LNX`` + fastboot_partition_alias_boot=LNX Variable overrides ------------------- +^^^^^^^^^^^^^^^^^^ Variables retrived through ``getvar`` can be overridden by defining environment variables of the form ``fastboot.<variable>``. These are looked up first so can be used to override values which would otherwise be returned. Using this mechanism you can also return types for NAND filesystems, as the fully parameterised variable is looked -up, e.g. +up, e.g.:: -``fastboot.partition-type:boot=jffs2`` + fastboot.partition-type:boot=jffs2 Boot command ------------- +^^^^^^^^^^^^ -When executing the fastboot ``boot`` command, if ``fastboot_bootcmd`` is set then -that will be executed in place of ``bootm <CONFIG_FASTBOOT_BUF_ADDR>``. +When executing the fastboot ``boot`` command, if ``fastboot_bootcmd`` is set +then that will be executed in place of ``bootm <CONFIG_FASTBOOT_BUF_ADDR>``. Partition Names -=============== +--------------- The Fastboot implementation in U-Boot allows to write images into disk partitions. Target partitions are referred on the host computer by @@ -115,11 +113,11 @@ their names. For GPT/EFI the respective partition name is used. For MBR the partitions are referred by generic names according to the -following schema: +following schema:: - <device type><device index letter><partition index> + <device type><device index letter><partition index> -Example: ``hda3``, ``sdb1``, ``usbda1`` +Example: ``hda3``, ``sdb1``, ``usbda1``. The device type is as follows: @@ -135,7 +133,7 @@ controller, SD/MMC controller) or disk index. The partition index starts from ``1`` and describes the partition number on the particular device. Writing Partition Table -======================= +----------------------- Fastboot also allows to write the partition table to the media. This can be done by writing the respective partition table image to a special target @@ -148,34 +146,26 @@ configuration options: CONFIG_FASTBOOT_MBR_NAME In Action -========= +--------- -Enter into fastboot by executing the fastboot command in U-Boot for either USB: - -:: +Enter into fastboot by executing the fastboot command in U-Boot for either USB:: => fastboot usb 0 -or UDP: - -:: +or UDP:: => fastboot udp link up on port 0, speed 100, full duplex Using ethernet@4a100000 device Listening for fastboot command on 192.168.0.102 -On the client side you can fetch the bootloader version for instance: - -:: +On the client side you can fetch the bootloader version for instance:: $ fastboot getvar version-bootloader version-bootloader: U-Boot 2019.07-rc4-00240-g00c9f2a2ec Finished. Total time: 0.005s -or initiate a reboot: - -:: +or initiate a reboot:: $ fastboot reboot @@ -184,9 +174,7 @@ and once the client comes back, the board should reset. You can also specify a kernel image to boot. You have to either specify the an image in Android format *or* pass a binary kernel and let the fastboot client wrap the Android suite around it. On OMAP for instance you -take zImage kernel and pass it to the fastboot client: - -:: +take zImage kernel and pass it to the fastboot client:: $ fastboot -b 0x80000000 -c "console=ttyO2 earlyprintk root=/dev/ram0 mem=128M" boot zImage creating boot image... @@ -197,9 +185,7 @@ take zImage kernel and pass it to the fastboot client: OKAY [ -0.000s] finished. total time: 2.766s -and on the U-Boot side you should see: - -:: +and on the U-Boot side you should see:: Starting download of 1847296 bytes ........................................................ @@ -212,3 +198,9 @@ and on the U-Boot side you should see: OK Starting kernel ... + +References +---------- + +.. [1] :doc:`fastboot-protocol` +.. [2] https://developer.android.com/studio/releases/platform-tools diff --git a/doc/android/index.rst b/doc/android/index.rst new file mode 100644 index 0000000000..225d6f125a --- /dev/null +++ b/doc/android/index.rst @@ -0,0 +1,14 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Android-specific doc +==================== + +.. toctree:: + :maxdepth: 2 + + ab + avb2 + bcb + boot-image + fastboot-protocol + fastboot |